LONDON - The Saudi exile Osama bin Laden, whom investigators were zeroing in on yesterday as a prime suspect in the most devastating attack on American soil since Pearl Harbor, has waged his ''holy war'' from caves in the mountains of Afghanistan backed by his fortune, his faith, his loathing for America, and what those around him describe as a death wish.

His grandiose vision of a global jihad, or Islamic holy war, against corrupt and secular governments of the Middle East and their US backers seemed like the plot from a bad action movie when he first began to shape it in the late 1980s.

But that vision, according to federal investigators, terrorism specialists, and even a former associate interviewed yesterday, became an American nightmare that before Tuesday seemed unimaginable.

The scion of a Saudi construction magnate who inherited a fortune that was in the hundreds of millions of dollars, bin Laden arrived in Afghanistan in 1987. He used muddy camps there to shape a ragtag group of holy warriors from around the Arab Muslim world, and instilled in them a single mission: to create an international network that would bring all Muslims under a militant and centuries-old interpretation of Islamic law.

His organization became known as Al Qaeda, Arabic for ''The Base,'' and it brought together Algerians, Egyptians, Palestinians, and Filipinos. It even attracted American Muslims who, once the Soviets were defeated in Afghanistan and the United States led the Persian Gulf War, joined their brethren in Al Qaeda and turned their well-honed skills against America.

US State Department documents show that Al Qaeda has up to several thousand members who are funded by bin Laden's roughly $300 million inheritance. The group has established a network of terrorist cells and operatives, known as ''sleepers,'' who investigators say were scattered around the world and across the United States, with an apparent concentration in New England.

Bin Laden also has strong family ties and a group of supporters in Boston, where the two hijacked planes used in the World Trade Center attacks departed. One of his brothers set up scholarship funds at Harvard, while another relative owns condominiums in Charlestown. Two bin Laden associates also once worked as Boston cab drivers.

The soft-spoken and devout 44-year-old, with his signature long beard, camouflage, and head scarf, is known by his associates as ''The Contractor,'' a nom de guerre that came from his family's background in the Saudi construction industry.

He was born in Jeddah, Saudi Arabia, one of 50 children to a father who had, by some estimates, 10 wives. He received a degree in public administration from King Abdul-Aziz University in Jeddah.

After he arrived in Afghanistan flush with cash and full of his grandiose plans, bin Laden began working on his mission, which some of his own fighters saw as implausible because of the fractious extremist elements within the Middle East.

There was the Egyptian terrorist group Gama al-Islamiya, which tried to topple Hosni Mubarak, the secular, US-backed president whom they considered corrupt. There also was the Algerian group GIA, which carried out its own bloody civil war to replace a brutal military regime with an Islamic state. The Pakistanis, the Palestinians, and the Sudanese each had very different agendas. Bin Laden pulled them all together.

Through the years, ''The Contractor'' built bridges between these groups and created orphanages, hospitals, and other development projects in Afghanistan.

During the 1980s, the United States supported the mujahideen, or Afghan resistance fighters, in their war against the Soviet Union, with an estimated $10 billion in covert aid that was funneled by the CIA.

''The reality was that this was their war, their jihad,'' said Milt Bearden, the former CIA station chief in Islamabad, Pakistan, who coordinated the mission.

In a telephone interview from Washington yesterday, Bearden added, ''We hijacked a piece of it because it met with our large policy objectives to defeat the Soviet Union. That was a point when you could say bin Laden didn't despise us. He didn't love us either.''

After the Soviets were defeated in Afghanistan, bin Laden moved to Sudan. He set up lucrative import-export businesses and a construction firm.

It was from his base in Sudan that his movement began to turn its rage toward the United States in the summer of 1990, when Saudi King Fahd permitted American troops to use Saudi Arabia as a staging ground for the Persian Gulf War, allowing a US-led alliance to liberate Kuwait from Iraqi dictator Saddam Hussein's invading army.

Investigators now believe the involvement of Al Qaeda in a 1993 attack on US troops stationed in Somalia may have been an early expression of bin Laden's hatred for the United States. Eighteen servicemen were killed in the attack, and the image of an American soldier being dragged through the streets became a searing image of America's vulnerability.

His title of The Contractor soon took on a different and more sinister tone after 1993, when bin Laden became known for financing, or contracting out, attacks through a network of underground terrorist organizations - Egyptian, Palestinian, Sudanese, and Pakistani - that carried out a truck bombing beneath the World Trade Center.

Evidence presented at a federal trial in Manhattan showed that the mastermind of the bombing, a Pakistan national named Ramzi Yousef, received wire transfers of money from bin Laden and that his computer files had contact numbers for bin Laden and associates. Authorities also believed Yousef served under bin Laden in Afghanistan.

Dan Byman, an specialist on terrorism and the director of research for the RAND Corp.'s Middle East Center, said bin Laden brought an administrator's touch to the fledgling movement.

''What stands out most about bin Laden is his managerial capabilities ... his long-term planning,'' Byman said. ''He managed to pull people together who would not even talk to each other a decade ago.''

Despite bin Laden's image for unifying extremist groups, there were those who resented him, said a former bin Laden associate who served in the brigade of Afghan resistance fighters who clustered around bin Laden in the late 1980s.

The man, who was granted political asylum in England in the early 1990s, said there were many who felt that bin Laden ignored the Palestinian cause and had done little to fund their efforts. He also said that some fighters were alienated by bin Laden's obsession with control and power and the way he used his wealth to keep that control.

''His persona is greatly exaggerated,'' the former fighter told the Globe through an interpreter yesterday on the condition of anonymity.

''He is a very religious man. He has become America's convenient monster.''

It was in February 1998 that bin Laden announced his intentions to the world.

He introduced The International Islamic Front for Jihad Against Jews and Crusaders, a new tent under which Al Qaeda and other militant factions from Egypt, Pakistan, Algeria, and Bangladesh gathered.

According to intelligence documents released by the US State Department, the front issued a chilling new ''fatwa,'' or religious decree: ''To kill Americans and their allies, both civil and military, is an individual duty of every Muslim who is able, in any country where this is possible.''

Such decrees are seen by Muslim scholars worldwide as a perversion of Islam, and adherence to such interpretations exists only on the farthest fringes of the faith, they say. But to bin Laden, these decrees helped unify his disparate followers.

On Aug. 7, 1998 - the anniversary of US military forces' entry into Saudi Arabia before the Gulf War - the front carried out its first action under the decree.

Two massive bombs exploded just hours apart at the US embassies in Kenya and Tanzania. According to intercepts by US intelligence officials, the plot was coordinated with phone calls made directly from the planners - an international force of Saudis, Jordanians, and others who traced their network to the Afghan resistance - to bin Laden.

The United States reacted by launching airstrikes in remote areas of Afghanistan where bin Laden was believed to be holed up. Over the next two years, the United States US exerted pressure on international governments to target Al Qaeda. More than 100 militants in 20 different countries from Jordan to England were arrested.

Meanwhile, bin Laden's Al Qaeda group kept up its busy work.

In 2000, the organization was linked to the daring attack of suicide bombers in a rowboat that blasted a hole in the USS Cole in Yemen, killing 17 sailors.

Azzam Tamimi, director of the Institute of Islamic Political Thought, based in London, has extensive contacts with the Afghan resistance fighters and traces bin Laden's anti-American sentiment back to 1994 when the Saudi government revoked his citizenship and froze his assets, at the request of the United States.

''It started on a personal, even petty level which he later endowed with religious sentiments,'' said Tamimi.

Bearden remains suspicious that even bin Laden did not have the capability to do this, certainly not alone.

''It is quite possible that bin Laden was the foil, or a kind of ruse to distract intelligence officials, from a much more sophisticated center of gravity,'' said Bearden.

Abdel-Bari Atwan, a senior writer for Al-Quds Al-Arabi newspaper, a leading Arabic-language daily in London, said bin Laden had planned a large-scale attack on American interests three weeks ago.

The writer, who has interviewed bin Laden and maintains contacts with his associates, said he remains convinced that ''all signs point to'' bin Laden's being behind this attack.

Atwan also said that bin Laden was sensitive about the criticism that he had not done enough to support the Palestinian cause, and that this week's attack could be an attempt to dispell that notion.

But Atwan said what is most important about understanding bin Laden was his feeling ''that he has lived too long.''

''He has said that he was in a hurry to meet his God,'' said Atwan. ''He wants to die as a martyr.''